This invention relates generally to battery chargers and more particularly to battery chargers with standby mode.
The battery packs for portable power tools, outdoor tools and certain kitchen and domestic appliances may include rechargeable batteries, such as lithium, nickel cadmium, nickel metal hydride and lead-acid batteries, so that they can be recharged rather than be replaced. Thereby a substantial cost saving is achieved.
A typical battery pack and charger are shown in FIG. 1. In such figure, a battery pack 10 is connected to a charger 20. Battery pack 10 may comprise a plurality of battery cells 11 connected in series and/or parallel, which dictate the voltage and storage capacity for battery pack 10. Battery pack 10 may include three battery contacts: first battery contact 12, second battery contact 13, and third battery contact 14. Battery contact 12 is the B+ (positive) terminal for battery pack 10. Battery contact 14 is the Bxe2x88x92 or negative/common terminal. Battery contact 13 is the S or sensing terminal. Battery contacts 12 and 14 receive the charging current sent from the charger 20 (preferably from current source 22, as discussed below) for charging the battery pack 10.
As shown in FIG. 1, the battery cells 11 are connected between the battery contacts 12 and 14. In addition, preferably connected between battery contacts 13 and 14 is a temperature sensing device 15, such as a negative temperature co-efficient (NTC) resistor, or thermistor, RT. The temperature sensing device is preferably in closer proximity to the cells 11 for monitoring of the battery temperature. Persons skilled in the art will recognize that other components, such as capacitors, etc., or circuits can be used to provide a signal representative of the battery temperature.
Battery pack 10 may also comprise an identifier as known in the prior art, so that charger 20 can identify the type and capacity of the battery pack, and charge accordingly.
The charger 20 preferably comprises a controller 21, which in turn includes positive terminal (B+) 16 and negative (Bxe2x88x92) terminal 17, which are coupled to battery pack 10 via battery contacts 12 and 14, respectively. The positive terminal may also act as an input, preferably an analog/digital input, in order for the controller 21 to detect the battery pack voltage. In addition, the controller 21 may include another input TC, preferably an analog/digital input, which is coupled to the temperature sensing device 15 via the third battery contact 13 (S). This allows the controller 21 to monitor the battery temperature. Controller 21 may include a microprocessor 23 for controlling the charging and monitoring operations. Controller 21 may control a charging power source for providing power to the battery pack 10, such as current source 22 that provides current to battery pack 10. This current may be a fast charging current and/or an equalization current. Current source 22 may be integrated within controller 21.
The charger 20, and its elements within, including controller 21, microprocessor 23, and current source 22, receive the necessary power from a power supply 24, which may be connected to a vehicle battery, a generator, or an AC outlet. Power supply 24 may convert the power received from the vehicle battery, the generator, or the AC outlet to the necessary power requirements of the different elements, as is well known in the art.
When the battery pack 10 is not connected to the charger 20, the typical charger 20 consumes energy, as full power is still provided to the elements the charger 20.
In accordance with the present invention, an improved battery pack charger is employed. The charger includes a controller, a battery power source connected to the controller, at least one terminal connected to at least one of the controller and the battery power source, a power supply connectable to an outside power source, the power supply providing power to at least one of the controller and the battery power source, and a switch connected between the outside power supply and the power supply, the switch being activated when a battery pack is connected to the at least one terminal.
The charger includes a controller, a battery power source connected to the controller, at least one terminal connected to at least one of the controller and the battery power source, a power supply connectable to an outside power source, the power supply providing power to at least one of the controller and the battery power source, and a switch connected between the power supply and at least one of the controller and the battery power source, the switch being activated when a battery pack is connected to the at least one terminal.
Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below.